Re: [Qemu-block] [Qemu-devel] [PATCH 3/4] docs: Document the l2-cache-full option

[Eric Blake]

On 07/24/2018 07:17 AM, Leonid Bloch wrote:
> Signed-off-by: Leonid Bloch <address@hidden>
> ---
>   docs/qcow2-cache.txt | 12 ++++++++----
>   1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/docs/qcow2-cache.txt b/docs/qcow2-cache.txt
> index a0a1267482..43c0faaddb 100644
> --- a/docs/qcow2-cache.txt
> +++ b/docs/qcow2-cache.txt
> @@ -110,11 +110,12 @@ How to configure the cache sizes
>   Cache sizes can be configured using the -drive option in the
>   command-line, or the 'blockdev-add' QMP command.
>   
> -There are three options available, and all of them take bytes:
> +There are four options available:
>   
> -"l2-cache-size":         maximum size of the L2 table cache
> -"refcount-cache-size":   maximum size of the refcount block cache
> -"cache-size":            maximum size of both caches combined
> +"l2-cache-size":         maximum size of the L2 table cache (bytes, K, M)
> +"refcount-cache-size":   maximum size of the refcount block cache (bytes, K, M)
> +"cache-size":            maximum size of both caches combined (bytes, K, M)
> +"l2-cache-full":         make the L2 cache cover the full image (boolean)
>   
>   There are a few things that need to be taken into account:
>   

Worth mentioning that the first three can be combined (although usually 
you'll never specify more than 2; as specifying all 3 requires that you 
perform the correct addition), but that the third is mutually exclusive?

> @@ -130,6 +131,9 @@ There are a few things that need to be taken into account:
>      memory as possible to the L2 cache before increasing the refcount
>      cache size.
>   
> +- If "l2-cache-full" is specified, QEMU will assign enough memory
> +  to the L2 cache to cover the entire size of the image.
> +
>   Unlike L2 tables, refcount blocks are not used during normal I/O but
>   only during allocations and internal snapshots. In most cases they are
>   accessed sequentially (even during random guest I/O) so increasing the

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org